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WPR15LA130 RV-6A Green Valley, AZ Non-fatal. PC published 08/25/2015

DeltaRomeo

doug reeves: unfluencer
Staff member
14 CFR Part 91: General Aviation
Accident occurred Saturday, March 21, 2015 in Green Valley, AZ
Probable Cause Approval Date: 08/25/2015
Aircraft: VANS RV6A, registration: N811KM
Injuries: 2 Minor.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The pilot reported that, after the airplane took off and reached an altitude of about 300 ft above ground level, the engine lost power. He then initiated a right turn toward the airport. Subsequently, the airplane impacted terrain and trees adjacent to the runway and nosed over. Postaccident examination of the airplane revealed that the right fuel pump power wire was disconnected at its terminal and that the left fuel pump power wire was partially disconnected from its terminal, which would result in no positive fuel pressure being supplied to the engine; the engine was not equipped with an engine-driven fuel pump. The examination also revealed that the crimp on the terminal connector for the right fuel pump power wire was likely incorrect, which allowed the wire to disconnect from its terminal; however, it could not be determined how the left fuel pump power wire became partially disconnected from its terminal. No additional anomalies were found during the examination of the airframe and engine that would have precluded normal operation. Based on the evidence, it is likely that the disconnection of both fuel pump power wires led to a loss of fuel pressure to the engine and the subsequent loss of engine power.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
?The total loss of engine power during initial climb due to the disconnection of both fuel pump power wires.

Full narrative:
On March 21, 2015, about 0920 mountain standard time, an experimental amateur built Vans RV-6A, N811KM, was substantially damaged during a forced landing following a loss of engine power during takeoff from the Ruby Star Airpark (14AZ), Green Valley, Arizona. The airplane was registered to Sunset Enterprises LLC and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. The private pilot and his pilot rated passenger sustained minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight. The cross-country flight was originating at the time of the accident with an intended destination of Tucson, Arizona.
In a written statement, the pilot reported that after takeoff from runway 6, at an altitude of about 300 feet above ground level, the engine lost power and he initiated a right turn toward the airport. Subsequently the airplane impacted terrain and trees about 100 feet from the runway and nosed over.

Examination of the airplane by local law enforcement revealed that both wings and fuselage were structurally damaged. The wreckage was recovered to a secure location for further examination.

Examination of the recovered airframe and engine revealed that the engine remained attached to the firewall via all its mounts. The carburetor was intact and disassembled. All internal components of the carburetor were intact. All six spark plugs were removed and the propeller was rotated by hand. Thumb compression was obtained on all cylinders. Throttle, mixture, and carburetor heat control continuity was established from the cockpit controls to the engine. All of the engine belts were intact and undamaged. The engine was not equipped with an engine driven fuel pump.

Battery power was applied to the airframe and the left and right fuel pump would not function. The positive power wire for the right fuel pump was disconnected from a quick disconnect terminal connector, which was enclosed within a plastic tube with electrical tape on one end. The positive power wire for the left fuel pump was connected to an insulated quick-disconnect terminal. The terminal halves were partially disconnected, enough where the inner metal terminals were disconnected. No additional anomalies were found during the examination of the airframe and engine that would have precluded normal operation.

The airframe and engine logbook records were not located.

http://ntsb.gov/_layouts/ntsb.aviation/brief2.aspx?ev_id=20150323X04916&ntsbno=WPR15LA130&akey=1
 
The idea is to put two electric pumps in the wing roots to provide positive pressure all the time in the fuel system. Allows the running of Ethanol auto gas. Has been talked about and done successfully by others on the forum.

It's unfortunate that the wiring what not better put together and or inspected in this critical function with the way this plane was setup.
 
Note that the report says "all six spark plugs"........................

I suspect maybe a Subie??

Yes, I know, no speculation-----------but the engine type is not in the case quote above as far as I can tell.
 
Why would you build a plane without an engine driven fuel pump?
especially a low wing. Am I missing something here?

Some engines don't have provisions for an engine-driven pump, some fuel injection systems don't work with engine-driven pumps. There are also possible advantages to locating the pump further upstream (like less susceptibility to vapor lock). Cars don't use engine-driven pumps.

Of course, going all-electric means you'd better have a reliable electric power source.
 
" ...power wire for the right fuel pump was disconnected from a quick disconnect terminal connector, which was enclosed within a plastic tube with electrical tape on one end... "

The takeaway for me is that the crimps were sub-standard and allowed the wires to pull out of the terminals. You could even read into the report that the builder knew the crimps were substandard, hence the electrical tape.

Crimping terminals is one of those jobs where only a really good tool (read: $$$) will do the job well enough for aircraft usage. Even more so where that crimp is critical to flight safety (electrically-dependent engine).

When building, at least take the time to give each crimped terminal a good yank of, say, 5 lbs for a 16-ga-sized wire as you'd typically use for a fuel pump.

Heinrich
 

When building, at least take the time to give each crimped terminal a good yank of, say, 5 lbs for a 16-ga-sized wire as you'd typically use for a fuel pump.

Heinrich


Just FYI...the NASA spec for an 18 AWG wire crimp is pull-out or fracture at no less than *32 pounds* of pulling force.

5 pounds is much, much too little force to properly test a crimp.
 
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